Supplementary information
18.16 CPU 410 cycle and reaction times
CPU 410 Process Automation/CPU 410 SMART
358
System Manual, 05/2017, A5E31622160-AC
Sequence of cyclic program processing
The table below shows the various phases in cyclic program execution.
Table 18- 9 Cyclic program processing
Step
Sequence
1
The operating system initiates the scan cycle monitoring time.
2
The CPU copies the values from the process output images to the output modules.
3
The CPU reads the status of inputs of the input modules, and then updates the process
image of the inputs.
4
The CPU processes the user program in time slices and executes the instructions spec-
ified in the program.
5
At the end of a cycle, the operating system executes pending tasks, e.g., loading and
deleting of blocks.
6
Finally, on expiration of any given minimum cycle time, the CPU returns to the start of
the cycle and restarts cycle monitoring.
Elements of the cycle time
Figure 18-27 Elements and composition of the cycle time
